Your smartwatch isn’t as accurate as you think

Sensors in today’s smartwatches can detect your heartbeat, track how you sleep and even monitor blood oxygen levels. We’re not far from your watch tracking your blood sugar … and possibly sending reports about it to your doctor.

Ever wondered, “Just how accurate are these smartwatch readings?” You’re not the only one, so I took a look. Smartwatches and fitness watches have some serious flaws you should know about.

Paging Dr. Watch! Emergency!

Turns out that cramming a bunch of sensors into a tiny watch doesn’t create the most legitimate results. Who knew? If you’re seeing spikes or drops in readings for sleep states or blood oxygen levels, don’t panic — it happens to everyone.

  • Sensors have problems with skin tone: A lawsuit filed against Apple says its Watch blood oxygen sensors don’t work correctly on dark skin. Yikes! Research, however, indicates this may be a problem with many blood oxygen sensors.
  • Smartwatches don’t reach medical levels of accuracy: High-grade studies are limited, but this one for Garmin fitness watches found they couldn’t measure energy expenditure or blood oxygen levels with enough accuracy to make medical decisions.
  • Step counters and calorie trackers are easily fooled: Smartwatches stink at measuring calories burned and can struggle to define steps walked. And don’t get me started on how vague sleep tracking can be!

OK, so smartwatches are only helpful for estimates. But what can we do to make them better?

Take your health in stride

Here are a few figurative steps I think all smartwatch users should take while getting in their literal steps (plus, a free play on words!).

  • Size your watch for your wrist: Many accuracy problems are caused by loose-fitting watches that slip around on your arm. Buy one with straps you can adjust.
  • Focus more on heart rate than steps or calories: Your pulse is right there, so it’s no surprise watches are more accurate about heart rate than almost anything else.
  • Don’t stress over readings: Ironically, that stress will increase your heart rate and other vitals. Even worrying about sleep tracking can cause inadequate sleep (doctors call it “orthosomnia”). Don’t think of readings as hard numbers but rather general brushstrokes about your health picture.
  • Watch readings over time: Those bigger-picture charts and graphs are more helpful than going number by number.
  • Visit a doctor if you’re worried: Don’t waste time or energy obsessing over what your smartwatch tells you. If you’ve got a serious concern, make an appointment like a grown-up.

‘Kim, which watch should I buy?’

This is one case where splurging on newer tech is actually better; the big-name smartwatches get more accurate with each new model. Here are the heavy hitters:

  • Use an iPhone? The Apple Watch Series 10 has all the bells and whistles, including ECG, fall detection and heart tracking. For a cheaper option, the 2nd-gen Apple Watch SE is under $200 right now.
  • In the Google-sphere? The Pixel Watch 3 is Google’s fancy-schmancy version — and way more affordable than Apple’s. For something more fitness-focused, a Fitbit is the way to go.
  • If your phone’s a Samsung: You might as well get the watch that “talks” to your phone best — the Galaxy Watch 7 is Samsung’s latest and greatest.
  • In it for health and wellness? I hear great things about WHOOP.

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Use an Apple watch? Make sure Fall Detection is turned on so you can get help if there’s an emergency. On your iPhone, open the Watch app, tap the My Watch tab > Emergency SOS. From here, you can choose Always on or Only on during workouts. Pick Always on.

Measure your heart rate with your phone

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You don’t need a fancy Apple Watch to get details on your heart health. With this trick, you just need a phone.

Urgent fire risk recall: For Belkin BoostCharge Pro fast wireless chargers. The iPhone and Apple Watch power pack launched in May 2023. Look for model number BPD005 on the back of your charging pad, and if you have one, stop using it immediately and fill out the refund form.

22 months later

A YouTuber got his Apple Watch back thanks to Find My. He lost it swimming and diving in the British Virgin Islands in 2022. A diver found the watch, powered it up and saw his contact info. The best part? It still works!

😴 Enable this on your Apple Watch: Sleep apnea is seriously dangerous, and the Series 9, Series 10 and Ultra 2 can spot the signs. Open the Health app on your iPhone, search for “breathing disturbances,” then tap Set up. Follow the directions on screen and you’re good to go.

We may receive a commission when you buy through our links, but our reporting and recommendations are always independent and objective.

“Do I have to charge you again?” Apple Watches have notoriously short battery life, but this can make a big difference. Open Settings > Display & Brightness > Always On. Disable the setting so your screen isn’t hogging your battery life all day long.

🤐 Respectfully, be quiet already: You remembered to mute your phone, but now, your Apple Watch is buzzing every 10 seconds. Open Settings > Focus > Do Not Disturb > Add New to activate or set up a schedule.

A remote you won’t lose: The latest OS for the Apple Watch, watchOS 11, got a snazzy upgrade people who lose the TV remote often are sure to love. With watchOS 11, you can turn the Digital Crown on your smartwatch to control the volume, and you can tap the three-dot menu button to mute or unmute and power your Apple TV on or off.

Airplane mode for the movies: Wear an Apple Watch? Theater mode silences your notifications when you don’t want your watch to light up or make a sound. Swipe up from your control center and tap on the Theater mode button (it looks like a happy face and a sad face side by side).

Have a heart condition? You might have a smartwatch to keep an eye on your ticker, but one in five users says they feel intense fear when they get an irregular rhythm notification. That extra anxiety isn’t helping your heart. If you have an Apple Watch, try taking some deep breaths with the Mindfulness app before you panic.

Apple Watch medical revolution

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More and more healthcare professionals are using Apple’s tech as a way to treat illness and disease.

Track your health: More doctors are incorporating the Apple Watch into patient care, especially for managing diseases. Case in point (paywall link): A woman with atrial fibrillation sends data from her watch to her doc to make sure her medication and lifestyle are on point. Want one? Check out the Apple Watch SE, Series 9 or Ultra 2.

We may receive a commission when you buy through our links, but our reporting and recommendations are always independent and objective.

🦁 “Cat” scan: A quick-thinking conservation vet used her Apple Watch to measure a lion’s heart rate in the wild. How? By wrapping the watch around its tongue. Didn’t have that one on my 2024 bingo card. You’ve gotta see the pic. Roar-some!

Apple Watch golfing apps

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Heading out to the green this weekend? Strap on your watch and check out these apps. 

Employees are suing over going back to work

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With the COVID emergency long gone, can employers fire workers who refuse to come back into the office? Plus, Apple Watch gets the FDA green light, why you should power down, and watch for this TSA scam.

Apple Watch who? Oura’s smart rings just got smarter with two new heart health features. The first compares your cardiovascular age to your real-life age and offers tips for improvement. The second estimates your VO2 max — the oxygen your body can use during intense exercise. Content Queen Allie wears one and loves it!

We may receive a commission when you buy through our links, but our reporting and recommendations are always independent and objective.

Apple Watch gets FDA approval

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Now, thanks to the Apple Watch, people with atrial fibrillation can actually detect when they’re experiencing an episode.

Apple win: The FDA just named the Apple Watch an official “medical device development tool” for its atrial fibrillation tracker. This means Apple Watches will soon collect data in clinical studies. It’s the first digital health device to achieve that status. Super cool. 

Smart devices for caregivers

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Got an Amazon Echo, Apple Watch, or smart locks? Here’s how they can come in handy when your loved ones need it the most.